Fuse link



INVENTOR.

` FUSE LINK Filed July 27, 1942 ,f Wj

Patented Aug. 14, 1945 FUSE LINK Chester W. Brown, Milwaukee 10, Wis., assignor to Line Material Company, Milwaukee, Wis., a

corporation of Delaware Application July 27, 1942, Serial No. 452,437

(ci. 20o-iii) 2 Claims.

This invention relates to spring fuse-links and has for its principal object to provide a fuse-link which can be assembled more expeditiously and, therefore, manufactured more cheaply than like devices heretofore known-without detracting in any respect from the quality of the product.

The fuse-link of the present invention is an improvement, from the standpoint of manufacturing economy, upon the constructions of Figures 2 and 3 of Steinmayer U, S, Patent No. 2,270,225.

The invention resides both in the new article of manufacture hereinafter described, by way of example, and in the improved method of assembly.

In the accompanying drawing Figs. 1 to 5, inclusive, illustrate successive steps in the operation of assembling the new fuse-link-the iinished product being depicted in Fig. 5. Fig. 6 is an enlarged cross-sectional view taken along the line 6-6 of Fig. 5.

The sub-assembly of Fig. 1 comprises an upper terminal member I having at its upper end a button-head contact II of conventional form. 'I'he shank of terminal member I0 is made of metal tubing which is flattened at I2 and unilattened at I3-shoulders being formed at I4 as a result of the flattening of portion I2.

Anchored to the lower end of terminal member I0 are the upper termini of a strain wire I5 and a fuse wire I6. The lower termini of which elements are attached lby soldering or otherwise to the upper end of a long flexible leader Il. There is no novelty in the sub-assembly of Fig. 1, per se.

'I'he next step in the assembling operation is illustrated in Fig. 2 and consists in attaching to the subassembly of Fig. 1 a bre tube IB and metal washer'IS. The washer serves as a seat for shoulders I4 and could be omitted. Shankl portion I3 is preferably a snug t in tube i8.

Thereafter, as depicted in Fig. 3, there is inserted in the lower end of tube I8 an ejector assembly comprising a close-wound helical spring 20 and an annulus 2I which is internally threaded (see Fig. 4) and thus attached to the lower end of the spring. Spring 20 is a close but free fit in the bore of tube I8, and annulus 2l functions as an abutment for anchoring the lower end of the spring to the lower end of the tube. As will be evident from the drawing, flexible leader Il extends axially through the ejector assembly coinprising spring 20 and annulus 2 I-said assembly being slipped over the end of the leader prior` to being inserted in tube I8.

The inside diameter of spring 20 is enough larger than the outside diameter of the leader to result in an annular space for the reception of a metal tubular sleeve 22 which, as shown in Fig. 4, is next slipped over the free end of the leader and pushed upwardly into spring 20. The upper end of spring 20 is constricted diametrically at 20a to form a. stop for engaging the upper end of sleeve 22.

By pushing upwardly on sleeve .22 (Fig. 4) spring 20 can be stretched and thus put under tension; and the amount of tension can easily be regulated and maintained uniformly at an optimum value through the use of a suitable tension-calibrated indicating tool in which either tube I8 or sleeve 22 can be held while the stretching of the spring is being carried out.

When the spring has been stretched to the specied tension, sleeve 22 is flattened, as indicated at 23, to effect a firm gripping engagement lvvithsthe leader. This is more fully illustrated in 'ihe fuse-link herein described functions in the saine manner as that oi Figs. 2 and 3 of the previously mentioned Steinmayer Patent 2,270,225. when the fusible section blowsl spring 20 collapses and ejects sleeve 22 together with leader il from the open end of the tube I8. The spring assembly itself drops out of the tube and may be carried along with the leader. The result is a practically instantaneous separation of the terminals within tube I8 between which the fusible section is normally connected. and this results in quick extihguishment of the arc.

- It will be manifest that the assembling operation herein described can be performed very rapiuiy and does not entail the exercise of a. high order of skill.

1 claim:

l i. The method of tensioning a strain type fuse link assembly including an insulating tube, a terminal secured to one end oi' said tube, a flexible leader extending out oi' the other end of the tube,

- and a. strain section interconnecting said terminal and leader, said method comprising passing the. free end of the leader through a helical spring and moving the spring to the interior of said tube, anchoring the corresponding ends of said tube and spring most remote from said terminal, passing the free end of the leader through a sleeve and moving the sleeve to the interior of said spring and into engagement with the end thereof remote from its anchored end, axially expandingthe spring by opposed relative movements of said tube and sleeve, and crimping the end of said sleeve upon said cable adjacent the disposed in said tube, the corresponding ends of said tube and spring being relatively anchored. and a sleeve disposed in said spring and surrounding said portion of said leader disposed in said tube, said sleeve engaging the end of said spring remote from said corresponding ends and projecting exteriorly of said tube and spring, the projecting end of said sleeve being crimped upon said exibie leader to hold said spring in exnortion of the flexible leader adjacent said fuse 10 panded tensioned condition.

section; of a contractile spring disposed in said tube and surrounding that portion of said leader CHESTER W. BROWN. 

